1. Field
The disclosed embodiments generally relate to the positioning of sheets in a feed path and in particular to paper registration using a stepper motor without employing micro-stepping techniques.
2. Brief Description of Related Developments
A translating electronic registration (TELER) system is a method of registering copy paper or documents. It generally includes three optical sensors, a pair of coaxial independently driven drive rolls, a carriage with a linear drive on which paper drive rolls are mounted, and a microprocessor controller. A copy sheet is driven into the nip rolls and moved through the paper path for placement and fusing of an image thereon. The speed of both nip rolls can be controlled to effect skew alignment and longitudinal registration. The nip rollers are mounted on a carriage movable transversely with respect to the feed path. A sensor system controls positioning of the carriage to achieve the desired top edge or a lateral positioning of the sheet. Independent control of nip roll drive and carriage translation provides simultaneous alignment in lateral and longitudinal directions. A translation electronic registration system of this type is disclosed in U.S. Pat. No. 5,094,442 to Kamprath et al. issued Mar. 10, 1992, the disclosure of which is incorporated by reference herein.
A stepper motor can be used to translate the driver rollers. In the TELER system, one of the two stepper motors must be advanced or retarded by a variable number of whole and partial steps to compensate for paper skew and lead edge registration. This is generally accomplished using micro-stepper or high performance DC servo systems that are very costly. Generally, stepper motor registration control designs require costly micro-stepping circuits and techniques. It would be helpful to perform precision paper registration using a stepper motor without employing micro-stepping techniques.